Conventionally, the public switched telephone network (PSTN) system will place a telephone number on an `Intercept` status if the number has changed or if the line has been disconnected. Calls placed to numbers on intercept, which therefore cannot be completed as dialed, are routed instead to an intercept system. Such system may provide a message to the caller with an appropriate announcement, determination of which may be made by accessing an intercept data base. For example, if the database indicates a change of the telephone number, the announcement can inform the caller of the new or `referral` number. If instead the called line has been disconnected without change of number, the message can notify the caller of the inactive status.
Known intercept systems are disclosed, for example, in U.S. Pat. No. 4,446,337 to Cofer and U.S. Pat. No. 4,791,666 to Cobb et al. The Cofer system delivers intercept messages that originate from the caller's originating switching office rather than at the destination office or an intermediate switching location. A message intercept condition can occur at the destination office or other location remote from the originating office. Such condition is signaled to the originating office and used to actuate a suitable announcement message apparatus. The originating office is equipped to forward an acknowledgement signal to the terminating office so that the trunk circuit can be released. The Cobb et al. system interfaces an electromechanical (EM) switching office having step-by-step or crossbar switching equipment with a remotely located digital changed number intercept system such as that disclosed by Cofer.
Directory assistance is a commonly provided service of the PSTN for a caller who does not know the directory number of the intended called party and does not have the appropriate "white pages" directory readily available. In response to a call placed to directory assistance, identifying the intended called party and address, a directory assistance data base equivalent to the white pages directory is accessed to obtain the directory number of the intended called party. If a change has occurred in the subscriber's status, such as termination of service or change in directory number or address, potential problems arise in providing accurate information. The data base may not have been updated with new material. Even if updated, the caller may not be aware of a new address that would be necessary to access the data base.
There is no standard interface between directory assistance and the conventional automatic intercept system. If the intercept number is contained in the directory assistance data base before updating has occurred, the caller upon obtaining the number, must place a new call to the intercept number to be provided with the appropriate intercept message. An additional call to the changed number, if such circumstances exist, may then be necessary to complete a call to the intended party. A more likely occurrence is that directory assistance has no information in its data base as to dropped telephone numbers and considerable time must be spent by a live operator to determine, often without success, the subscriber status of the intended called party and whether a new directory number is active for that party. A similar drawback exists in situations in which the directory assistance data base contains a new listing for a subscriber who has moved to a new address. If the caller is not aware of the change of address, input to directory assistance of the old address will present difficulty in finding the intended called party's directory number. If the subscriber name is a common name associated with several listings at different addresses, or the subscriber name is a business having several directory listings, obtaining accurate information is further complicated.
Examples of directory assistance systems are described in the following patents. U.S. Pat. No. 4,979,206 to Padden et al. and U.S. Pat. No. 4,959,855 to Daudelin disclose an automated directory assistance system using speech recognition and speech synthesis technology. The caller is given the option to complete a call to the station identified by a retrieved directory listing. U.S. Pat. No. 5,181,237 to Dowden et al. discloses a system for automatically processing operator assistance type calls, without actually connecting the calls to a live operator. The system includes an automated position group, having speech recognition facilities and announcement capabilities, to replace the functions of a human operator. U.S. Pat. No. 4,922,519 to Daudelin discloses an automated operator assistance calling system. An operator assistance switch initially connects the calling customer to a voice processing unit and prompts the customer to speak a command or key a command code identifying the desired class of call, for example a person-to-person call. The command/code is recognized and used to direct the flow of the control program to selectively defer a connection to an operator position. U.S. Pat. No. 4,918,719 to Daudelin discloses an automated announcement system for processing directory assistance and/or intercept calls. The disclosed system permits connection to an operator after completion of the announcement, for example in response to speech from the caller.
U.S. Pat. No. 5,339,352 to Armstrong et al. discloses a directory assistance system in which a call may be completed, upon request, by the system to the station identified by the retrieved listing. This feature is particularly useful if the caller is using a wireless communication device.
None of these prior art systems enables a call dialed to directory assistance to be automatically referred to an intercept handling system. Thus, at present, a caller who refers to personal records or an old telephone book to identify an out-of-date directory number will be connected to the intercept system by dialing the old number; if that person instead calls directory assistance, either the correct information will be reached through great effort by the directory assistance operator or no information will be obtainable. In either case, an unacceptably long delay in the directory assistance call would occur. Such delays are annoying to callers and extremely costly to the telephone company.